1. Field of the Invention:
The present invention relates to a servomechanism having a housing, a stator with at least one stator winding, the stator being firmly connected with the housing, and a rotor with at least one rotor winding, the rotor being mounted in the housing via a rotor shaft.
2. Description of the Prior Art
Servomechanisms which are also known as synchros or resolvers are used for the transmission of angular information. The structure and operation of these servomechanisms are described, for example, in the publication "Funktechnik" 1970, pp. 14-16 and 49-52. In the conventional structure of servomechanisms, the stator and the rotor are respectively composed of laminated stacks having slots therein in which one or more windings reside. The rotor windings are connected either via sliding contacts or via a rotatable transformer. Due to the air gap between the stator and the rotor, a primary winding and a secondary winding are therefore coupled with each other. When an alternating voltage energized the primary winding, it generates a secondary voltage in the secondary winding, which is varied between 0 and a maximum value, depending on the angular position between the stator and the rotor.
In the case of the above-described structure of the conventional servomechanisms, a so-called null-voltage is caused by the coil winding head, i.e. by the non-active part of the winding and by different magnetic saturation in the sloted, laminated stacks of the stator and the rotor, the null-voltage causing in a connected servosystem an undesired additional heating. This null voltage is additionally influenced by the sharpening burr at the slot edges and metal separation points of the stator stack and the rotor stack. Another error source in a servomechanism is the first harmonic wave in the electrical error, caused by winding insertion errors, errors in the number of turns in individual coils or by magnetic asymmetry in the iron circuit. Such asymmetry result from out-of-roundness of the stator bore or of the outer diameter of the rotor, as well as from eccentric integration of the laminated stacks and also from irregular layering of the laminated stacks because the metals, in and across the grain, have a different magnetic conductivity approximately in a ratio of 4:1. Also, the slots in the rotor and in the stator influence, via harmonics of the slots, the electrical error of the servomechanism.
For certain applications, the conventional servomechanisms are also too long in the axial direction. Although one could reduce the structural length for the corresponding change of the construction, such changes require very high investments in manufacturing for each variation. Furthermore, the above-described disadvantages of this structure would still not be eliminated given a shortening of the axis.